I need help understanding Assassin's Creed Brotherhood?

in brother hood Ezio (dude from ac2) hid the apple of eden. and the guy in real life not back in the 1500 with ezio but the current part has to go threw all of ezio's memorys in the machine thing to find out where the apple of eden is hidden before the world ends. but when you are ezio you go threw him hiding it and other stuff